A possible shortcut for neutron–antineutron oscillation through mirror world

Existing bounds on the neutron-antineutron mass mixing, ϵnn¯< few × 10 - 24 eV, impose a severe upper limit on n- n¯ transition probability, Pnn¯(t)<(t/0.1s)2×10-18 or so, where t is the neutron flight time. Here we propose a new mechanism of n- n¯ transition which is not induced by direct mass mixing ϵnn¯ but is mediated instead by the neutron mass mixings with the hypothetical states of mirror neutron n′ and mirror antineutron n¯ ′. The latter can be as large as ϵnn′,ϵnn¯′∼10-15 eV or so, without contradicting present experimental limits and nuclear stability bounds. The probabilities of n- n′ and n- n¯ ′ transitions, Pnn′ and Pnn¯′, depend on environmental conditions in mirror sector, and they can be resonantly amplified by applying the magnetic field of the proper value. This opens up a possibility of n- n¯ transition with the probability Pnn¯≃Pnn′Pnn¯′ which can reach the values ∼ 10 - 8 or even larger. For finding this effect in real experiments, the magnetic field should not be suppressed but properly varied. These mixings can be induced by new physics at the scale of few TeV which may also originate a new low scale co-baryogenesis mechanism between ordinary and mirror sectors.